Multipass illumination of an elongated zone

Abstract

A system for providing multiple traversal illumination of a region with a beam of radiation wherein the illumination provides substantial but not complete overlap at each repeated pass of the beam throughout the region. Because there is a slight shift in direction of the beam on each traversal of the region, it is possible to apply the beam and extract it after a predetermined number of traversals, and means are provided for this purpose. In addition, more than one beam may be applied to the same region, each having a different, predetermined number of traversals before extraction. In this manner, a form of beam combination is achieved.

What is claimed is: 
     
       1. A system for providing multipass illumination of a three-dimensional zone extending in an axial direction comprising: a source of radiation;   means for directing radiation from said source axially into said zone;   means for reflecting said radiation on a plurality of traversals through said zone each succeeding traversal substantially but not completely overlapping the portion of said zone illuminated by the preceding traversal; and   means responsive to radiation passing through said zone after a predetermined number of traversals for inhibiting further passage of said radiation through said zone.   
     
     
       2. The system of claim 1 wherein said reflecting means includes a reflector. 
     
     
       3. The system of claim 2 wherein said reflector includes a plain mirror. 
     
     
       4. The system of claim 1 wherein said reflecting means includes focusing means. 
     
     
       5. The system of claim 4 wherein said focusing means provides a image outside of said zone of a substantially central plane within said zone orthogonal to said axis. 
     
     
       6. The system of claim 1 wherein said reflecting means includes: a first concave mirror responsive to radiation from said zone for direction thereof away from said zone;   a second concave reflector responsive to radiation directed away from said zone by said first concave reflector for reflecting radiation back toward said first concave reflector and ultimately back toward said zone.   
     
     
       7. The system of claim 6 wherein said first concave reflector provides an image of the surface of said second concave reflector within said zone. 
     
     
       8. The system of claim 6 wherein said first and second concave reflectors are cylindrical reflectors. 
     
     
       9. The system of claim 8 wherein said first and second concave reflectors have the axes of the imaging cylinders of which they are a part orthogonal to each other. 
     
     
       10. The system of claim 6 wherein said first and second concave reflectors are spherical reflectors. 
     
     
       11. The system of claim 1 wherein: said reflecting means includes first and second concave reflectors; and   said directing means includes a further reflector responsive to radiation from said source for directing said radiation towards said first concave reflector for direction axially through said zone;   said first concave reflector positioned to receive radiation from said zone for direction toward said second concave reflector with said second concave reflector positioned to reflect the radiation incident thereon back toward said first concave reflector for direction through said zone;   said first and second concave reflectors having a focal plane for radiation in said zone between said first and second concave reflectors;   the radiation having a minimum waist dimension at said focal plane with the position of said minimum waist upon said focal plane varying from one traversal to another traversal of said zone by said radiation.   
     
     
       12. The system of claim 11 further including: means for expanding the dimensions of said focal plane.   
     
     
       13. The system of claim 12 wherein said expanding means includes a convex and concave reflector between said first and second concave reflectors. 
     
     
       14. The system of claim 11 further including means for intercepting the radiation substantially at said focal plane after a predetermined number of traversals thereby to inhibit further traversals of said zone by said radiation. 
     
     
       15. The system of claim 14 wherein said inhibiting means includes means for reflecting said radiation away from said zone. 
     
     
       16. The system of claim 13 wherein said further reflector has its reflecting surface located substantially at said focal plane. 
     
     
       17. The system of claim 1 further including means for separating isotopes with said zone being defined as an interior region of said means for separating isotopes. 
     
     
       18. The system of claim 17 further including means for directing a flowing vapor of a plurality of isotopes, one of which is to be separated therefrom, through said zone. 
     
     
       19. The system of claim 17 wherein said radiation source includes means for providing plural radiation frequencies adapted for producing isotopically selective photoexcitation. 
     
     
       20. The system of claim 1 wherein: said radiation source provides radiation of plural different frequencies;   said directing means includes means for inhibiting further traversals of said zone at different predetermined numbers of traversals for the radiation of different frequencies.   
     
     
       21. The system of claim 1 wherein: said reflecting means has at least one focal plane which is reimaged parallel and at least proximate to itself by said reflecting means.   
     
     
       22. The system of claim 1 wherein: said reflecting means includes plural reflectors with the surface of at least one reflector imaged to a plane within said zone.   
     
     
       23. The system of claim 1 wherein the image plane is central within said zone and correspondes to the location of the plane at which the surface of another of said plural reflectors is imaged. 
     
     
       24. The system of claim 1 wherein said reflecting means includes plural reflectors with the surface of one imaged to a plane on an opposite side of said zone. 
     
     
       25. The system of claim 1 wherein the image plane is proximate of another of said plural reflectors, said other of said plural reflectors being a plane reflector. 
     
     
       26. A reflective system for providing substantially overlapping multiple traversals of a region to be illuminated by radiation wherein each suceeding traversal of radiation substantially but not completely overlaps the portion of the region illuminated by the preceeding traversal comprising: first and second reflective systems positioned at opposite ends of said region to be illuminated;   said first and second reflective systems each having respective optical axes associated therewith, the optical axis of one of said reflective systems projected to the other reflecting system forming an angle to the optical axis of said other reflecting system.   
     
     
       27. The system of claim 26 wherein: at least one of said first and second reflective systems having associated therewith a focal plane to which parallel radiation in said region is focused.   
     
     
       28. The system of claim 26 wherein at least one of said first and second reflective systems includes at least first and second curved reflectors with the first curved reflector optically closer to said region than the second curved reflector and providing an image of said second curved reflector in a region between said first and second reflective systems. 
     
     
       29. The system of claim 28 wherein said first and second reflector systems are substantially the same. 
     
     
       30. The system of claim 28 wherein the other of said first and second reflective systems is a plane reflector. 
     
     
       31. The system of claim 28 further including: reflector means adjacent at least one of said focal planes adapted for diverting radiation from reflection through said region; and   means proximate to at least one of said focal planes for diverting radiation into said region.   
     
     
       32. The system of claim 28 further including: means for expanding the dimensions of said focal plane.   
     
     
       33. The system of claim 32 wherein said means for expanding the dimensions of said focal plane includes a convex mirror.